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The New Movement in UL Firestop Certification Programs

While it may be common for elements of building construction to shift during the various phases of a building’s lifespan, does this movement negatively affect the firestop system’s ability to serve its intended fire protective function?

firestop movement “test” image

September 11, 2020

Authored by: Luke C. Woods, Principal Engineer - Fire Resistance and Containment

It may be common for elements of building construction to move or shift during the various phases of a building’s lifespan. Such movement can be driven by human contact, but may also be due to thermal cycling, building settlement, seismic activity, mechanical vibration and more. Some construction elements, such as expansion joints, are designed for movement and have been tested and evaluated for these conditions. Regardless of the mode, firestop systems may also be subject to such movement. When movement occurs a number of questions come to mind: Does the movement negatively affect the firestop system’s ability to serve its intended fire protective function? After movement, is the condition of the firestop system still as specified in the UL firestop design? Is there confidence that the firestop system’s performance characteristics are undiminished? If not, how can we gain such confidence? Part of the answer is to consider UL Certified firestop systems complying with both ASTM E3037, Standard Test Method for Measuring Relative Movement Capabilities of Through-Penetration Firestop Systems, and UL 1479, Standard for Fire Tests of Penetration Firestops. 

UL has deployed a new rating associated with UL Certified firestop systems that confirms that a system complies with the requirements of UL 1479 after the simulated movement exposure defined in ASTM E3037. This rating – designated as an “M Rating” – represents the amount of movement a specific firestop system can accommodate while still satisfying the fire and hose stream requirements of UL 1479. In some respects, this aligns with the testing and certification protocol of UL 2079, Standard for Tests for Fire Resistance of Building Joint Systems, that evaluates fire resistive joint systems for their ability to prevent the effects of fire from transmitting from one side of the fire resistant barrier to another through the fire resistant joint and for dynamic joint systems to maintain the fire protective characteristics after simulated cyclic movement. 

As mentioned previously, the new M Rating is based on a firestop system’s ability to comply with both ASTM E3037 and UL 1479, factoring in several variables. These include the type and size of the penetrant, size of the annular space, firestop material(s) and direction of movement as defined by ASTM E3037, e.g., Y direction or Z direction, parallel or perpendicular to the plane of the supporting construction, respectively. M Rated UL firestop certifications are identified within individual certification designs through a table describing the potential movement capability based on indicated parameters. It is also important to verify if the firestop system can still maintain ancillary performance ratings, such as L (air leakage) or W (water leakage) ratings, when the M Rating is included. The movement table will identify if the L or W rating(s) are maintained or ineligible.

An example of this information is shown below.

Firestop Movement Table

As this program evolves, more UL Certification designs will include M Ratings so be sure to look for the M Rating details.

For more information regarding the UL Movement Certification Program, please visit for a free, 30-minute educational webinar explaining the mechanics of the test method and the requirements of the UL Certification program.

The Movement in Firestops Webinar

Learn how fire stop movement testing and certification can help assess a product’s ability to stop the spread of fire between building compartments.

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Additional resources

Standardizing Firestop System Movement Certification to Improve Building Safety Stopping

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